Corroboration of faster annual growth rate of black anglerfish (Lophius budegassa) in Spanish Mediterranean based on length frequency analysis

Abstract

The illicium (first dorsal fin ray) has become the standard structure for age estimation of black anglerfish (Lophius budegassa) in most of the European countries and the one used as a basis for stock assessment, after calibration exchanges among the age readers and workshops. However, the tendency in the past to not pay essential attention to the need to validate or corroborate the age estimation in some stocks has led to misunderstanding of their dynamics. Thus, the Atlantic black anglerfish stocks have not been annually assessed using age-structured models during the last years in ICES working groups due to problems with the data quality, including those coming from a biased illicia age estimation criterion. The same age estimation criterion is used for the Mediterranean black anglerfish. Evidence obtained in the last years, using alternative methodologies to the age 263 estimation, have shown a faster growth rate of black anglerfish. Some growth increments considered as annuli in illicia do not seem to be really annual. The growth pattern of black anglerfish in Spanish Mediterranean waters is analyzed in this study using the length-frequencies (lengths ranging 3-128 cm) of annual groundfish research surveys between 2004 and 2012. The results corroborate that the growth pattern of the Mediterranean population of this species is also faster than that estimated applying the traditional illicia age estimation criterion. The von Bertalanffy growth parameters are also estimated and compared to those of previous studies; they will be available if a length-structured model including growth parameters is used in the assessment of this Mediterranean stock.